Add missing checks for doc(cfg_hide(...)) attribute

compiler/rustc_error_messages/locales/en-US/passes.ftl

@@ -145,6 +145,9 @@ passes_doc_test_takes_list =
 passes_doc_primitive =
     `doc(primitive)` should never have been stable
 
+passes_doc_cfg_hide_takes_list =
+    `#[doc(cfg_hide(...)]` takes a list of attributes
+
 passes_doc_test_unknown_any =
     unknown `doc` attribute `{$path}`
 

compiler/rustc_passes/src/check_attr.rs

@@ -934,6 +934,22 @@ impl CheckAttrVisitor<'_> {
         is_valid
     }
 
+    /// Check that the `#![doc(cfg_hide(...))]` attribute only contains a list of attributes.
+    /// Returns `true` if valid.
+    fn check_doc_cfg_hide(&self, meta: &NestedMetaItem, hir_id: HirId) -> bool {
+        if meta.meta_item_list().is_some() {
+            true
+        } else {
+            self.tcx.emit_spanned_lint(
+                INVALID_DOC_ATTRIBUTES,
+                hir_id,
+                meta.span(),
+                errors::DocCfgHideTakesList,
+            );
+            false
+        }
+    }
+
     /// Runs various checks on `#[doc]` attributes. Returns `true` if valid.
     ///
     /// `specified_inline` should be initialized to `None` and kept for the scope
@@ -987,6 +1003,13 @@ impl CheckAttrVisitor<'_> {
                             is_valid = false;
                         }
 
+                        sym::cfg_hide
+                            if !self.check_attr_crate_level(attr, meta, hir_id)
+                                || !self.check_doc_cfg_hide(meta, hir_id) =>
+                        {
+                            is_valid = false;
+                        }
+
                         sym::inline | sym::no_inline
                             if !self.check_doc_inline(
                                 attr,

compiler/rustc_passes/src/errors.rs

@@ -271,6 +271,10 @@ pub struct DocTestUnknown {
 #[diag(passes::doc_test_takes_list)]
 pub struct DocTestTakesList;
 
+#[derive(LintDiagnostic)]
+#[diag(passes::doc_cfg_hide_takes_list)]
+pub struct DocCfgHideTakesList;
+
 #[derive(LintDiagnostic)]
 #[diag(passes::doc_primitive)]
 pub struct DocPrimitive;